The study seeks to investigate the various glucose interactions in the glycogen storage diseases. The approach includes the evaluation of hydrolysis and absorption of cooked and uncooked starches, determination of hepatic glucose production and determination of the flux of glucose metabolites. The investigation of the responses of children with Type I glycogen storage disease to the administration of different raw starches suggests interfamily differences in the rate of hydrolysis, suggesting polymorphism of pancreatic amylase. The study of the rate of glucose production by the liver of patients with Type I GSD using 13C-glucose has been initiated. In addition to determining the rate of glucose production by the liver, we will follow the pattern 13C into the Kreb cycle intermediates.